Land disposal is one of the most important topics when it comes to solid waste disposal. Land disposal techniques are categorized into 3 types.
- Underground injection
- Farming and
Land Disposal Techniques – Underground Injection
In a location where the environment is suitable, it is possible to inject potentially hazardous waste underground. Deep-well injection has been used to dispose of organic solution from refinery of petrochemicals, chemicals, paper, and pharmaceutical plants. Testing of the hazardous waste should be carried out prior to selecting this method of disposal. The acceptable waste should be free from suspended or clogging solids and material that will react adversely with the substance into which it is being injected. The suitable underground environment should be permeable to a point of final residence and isolated from any water sources. To determine the suitability of the underground site, a well is drilled and various depth core samples are analysed for specific characteristics relating to its permeability and reactivations with the waste. Tests will also confirm the injection pressures required at various waste flow rates. Underground soils may be treated to improve permeability to reduce the injection pressure required.
Certain precautions are necessary as there are danger of (1) contaminating water supplies by later migration of the hazardous waste or even by vertical migration though open subsurface or mechanically failed soil structures, and (2) causing movement of geological faults leading to potential earthquakes in the area. In this case, the waste acts as a lubrication between two adjacent underground slabs of rock faults causing them to move apart easily.